Members of the board that investigated the demise of the space shuttle Columbia said Monday they were encouraged that NASA leaders are listening to dissenting opinions but wondered why the agency overruled a top safety officer last week on a crucial decision.
NASA's top leaders decided at a meeting Thursday to put off any further design changes to the space shuttle's external fuel tank until after Discovery's flight in July, despite concerns raised by engineers, including Bryan O'Connor, the space agency's chief safety officer.
The agency had been considering changing the design of the tank's 34 so-called ice frost ramps to stop insulating foam from falling off. Meeting participants were split, but top leaders decided it was best to see how recent changes to the tank held up before making any more modifications, space shuttle program manager Wayne Hale said last week.
Foam breaking off the external tank at liftoff doomed Columbia and its seven astronauts in 2003.
In an e-mail Monday, O'Connor said he had recommended redesigning the ramps before the next flight, but NASA Administrator Michael Griffin favored the opinion of the program manager and an associate administrator to fly "as is," with plans to develop a new design for future flights.
"I believe the discussion of options and their risk trades were carried out professionally and with due respect to all opinions," O'Connor said. "The agency accepts the risk of flying the current configuration with its eyes open."
Last week's meeting illustrated that the space agency may have learned a major lesson from management problems leading up to Columbia's disintegration upon re-entry, said Adm. Harold Gehman Jr., former chairman of the now-disbanded Columbia Accident Investigation Board.
"The old NASA would have rolled over dissent," said Gehman, whose board concluded that dissent was discouraged before the accident.
But James Hallock, a Department of Transportation safety official, said he wished he knew more abut why O'Connor was overruled. If you're not going to listen to the safety officer, "Why do you have one?" he said.
Sheila Widnall, an aeronautics professor at the Massachusetts Institute of Technology who also served on the board, said she was still concerned that NASA hadn't solved the tank's foam problem. The tank was redesigned for the first post-Columbia flight last July, but foam still came off.
"The thing I don't know ... is why have the different approaches NASA has taken not been satisfactory?" Widnall said.
Douglas Osheroff, a physics professor at Stanford University who served on the board, said he worried that NASA was facing political pressure to fly in July.
"These guys are under an awful lot of pressure," Osheroff said. "I surely would not want to be in Griffin's shoes right now."